Reinforced wire-contacting insulator assembly



R. CASE March 9, 194s.

REINFORCED WIRE-CONTACTING INSULATOR ASSEMBLY Filed Nov. 24, 1945E1.vent0r liegers Case Patented Mar. 9, 1948 EEENFORCED WIRE-CONTACTINGINSULATOR. ASSEMBLY I Rogers Case, Orange, N. J.

Application November 24, 1945, Serial No. 630,588

2 Claims. i

This invention relates to a wire-contacting insulator assemblyreinforced by additional protection against short-circuiting if the mainelectrically insulating body of the assembly should be broken.

Tensioning .and transposition brackets for communication lines are madeto bemounted in the lines between poles in suspended relation with thewires. When brackets of that sort are organized to include insulators ofgeneral spool form, those insulators are made of some highly frangiblematerial, such as glass or porcelain, and are mounted on a metal base bymeans of metal. insulator pins. Breakage of such insulators isrelatively frequent and may be caused by accident, mischief, or malice;and when an in sulator which is incorporated as an element in a'metaltensioning or transposition bracket of the indicated sort is broken,such breakage is almost sure to result in a short-circuit. This isbecause relative movement between the line wire and the base of thebracket when the insulator is broken and the relief of the tension underwhich the wire is held brings it into contact with the metal pin onwhich the insulator is mounted,

or into contact with some other metal part of the bracket.

The primary object of my invention is to provide in line-tensioning andtransposing bracket assemblies and other mounted wire-contactinginsulator assemblies, insulator structures comprising what may beconsidered as insulation reinforcement, or emergency insulation, toprevent short-circuiting when the frangible body of an insulator isbroken, and to keep the line in service until the broken insuiatorisreplaced.

A corollary object of the invention is to provide such insulationreinforcement, or emergency insulation, by means of a simple andinexpensive addition to the insulator structure.

In the accompanying drawings illustrative of a physical embodiment of myinvention:

Fig- I is a plan view of a tensioning and transposition bracketconstructed to be mounted in communication lines, and showing theimproved insulator structure of my invention incorporated .as an elementthereof.

Fig. II is an end elevation of the transposition bracket shown in Fig.I, looking upwardly of the sheet.

Fig. III is an enlarged cross-sectional view through the structure atone side of the bracket, taken in the plane of the section line IIIIIIof Fig. I, and showing the body of one insulator removed as by breakage,to illustrate the mannor in which a short-circuit is prevented underthat condition.

The transposition bracket shown in the drawings is, save for theimprovement of my present invention, made in accordance with my priorPatent No. 2,356,750. Thus it comprises a metal frame, or base, i onwhich a plurality of spoolf'orm insulators 2, 3, 4 and 5 are mounted inapproximately rectangular arrangement in their position relatively toeach other. The insulators 2 and 3 form one diagonally arranged pairextended upwardly from the base I, and insulators i and 5 form a seconddiagonal pair extended downwardly from the base I. Each of theinsulators is carried by a bolt, or pin, 6 which as shown comprises ahead 1, and is secured in position by a cotter pin 8.

In service position of the transposition bracket it is suspended on theline wires A and B of a communication line, with the line wires A and Btransposed in their relative position in the line by being trainedrespectively around the two diagonal pairs of insulators 2-3 and 4-43.Thus the line wire A is trained over insulator 2 and diagonally acrossthe line spaced by the bracket to and against insulator 3. Both of theseinsulators 2 and 3 extend upwardly from the base i of the bracket.Similarly the line wire B is trained over insulator 4 and broughtdiagonally across the bracket and across line wire A to insulator 5around which it passes. t readily will be understood that the line wirestrained over the insulators are placed under tension and exert a bendingforce on the pin 6 of each insulator. To oppose this destructive pull ofthe line wires, and to prevent bending of the insulator pins, each. ofthe pins is braced in opposition to the forces exerted by the wire whichis trained against it by a metal brace 9 riveted to the base I andengaging the pin 8 of the insulator.

In service the transposition bracket thus is suspended on the line wireswith one Wire, such as the wire A, overlying the metal base of thebracket, and the other wire, such as the line wire B, underlying thebase of the bracket. The width of the bracket and the spacing of theline wires normally is such that both wires are placed under tension. Onbreakage of either of the insulators 4 and 5 a short-circuit is formedby direct contact between the wire B and a metal part of the bracket.This is becausethe tension under which the wire is placed brings itinwardly into contact with the pin 6 of the broken insulator. Alsorelative movement between the wire and the bracket causes the wire tomove along the insulator pin 6 into contact with the metal base I, sothat even if the insulator pin should be insulated from the base, or'thewire should escape direct contact with the pin, a short-circuit is made.In the case of the line wire A which overlies base I of the bracket, theformation of a short-circuit when one of the insulators 2 or 3 is brokenalso is almost certain. This is because the tension of the wire andtilting of the bracket when the insulator is broken brings that wireinto contact with the metal pin 6 of the broken insulator, and finallyinto contact with one of the metal braces 9 which support the insulatorpins against the bending forces exerted on them by the wire.

The problem arising from the danger of shortcircuiting by breakage of aninsulator being serious, various expedients have suggested themselvesior preventing short-circuiting when an insulator is broken. One suchexpedient is to insulate the base of the bracket and the insulator pinsby applying to them a coating of vitreous enamel. lSuch expedient isrelatively expensive and is ineffective, because a vitreous coating onthe base and insulator pins of the bracket is itself susceptible tobreakage, chipping and spalling. I have discovered, however, that in awire-tensioning and transposition bracket the danger of short-circuitingupon breakage of an insulator can in practical efiect be eliminated byvery simple and inexpensive means. Such means consists of a linersleeve, such as the liner sleeve designated by reference numeral I inthe accompanying drawings, which is composed of tough electricalinsulating material, and which surrounds the mounting pin of eachinsulator to lie between the pin and the insulator body.

Referring to the drawings, it will be seen that the tubular portion ofliner I0 is provided at one end with a laterally extended flange, orskirt, I I which lies against the upper end of the insulator body tosurround the pin-receiving bore I2 therethrough. As shown particularlyin Fig. III of the drawings, laterally extended flange, or skirt, II ofthe liner sleeve lies in a countersunk seat, or outwardly open recess,I3 formed in the structure of the insulator body around the boretherethrough. In the bracket assembly shown, the liners ID are soarranged in the bodies of the insulators that their extended skirts l Iare at the upper ends of the insulator bodies. That is, in the case ofthe insulators 2 and. 3, flanges I I of the liners forming part of thoseinsulators are between the upper end of the insulator and the braces 9which engage the insulator pin of each. In the case of insulators 4 and5 which extend downwardly from the base I of the bracket, the flanges IIof the liners Ill forming part of those insulators lie against the endof the insulator body which is adjacent the under surface of the base.

Assuming that the body of one of the insulators 2 or 3 which extendupwardly from base I, or of the insulators 4 or 5 which extenddownwardly from base I, be broken, the wire trained around the brokeninsulator tends, as previously described, to move both upwardly andinwardly with respect to the base of the insulator. Also the base of theinsulator tends to tilt as the balancing effect of the symmetricalgrouping of the insulators with respect to the line wires is lost. Ifthe insulator be merely cracked, or there be a gap in it, there may beno substantial relative movement between the base of the bracket and thewire, and in such case the tubuin the drawings.

lar portion of liner sleeve III of the broken insulator preventsshort-circuiting between the wire and the insulator pin, because of itsembracing relationship with the pin, If, however, there be movement ofthe sort described, which usually will occur if the broken insulatorbody be entirely detached from its pin, the wire moves inwardly until itrests against the tubular portion of the liner, and in its upwardmovement reaches and comes to rest at the junction between the tubularportion of the liner and the flange, or skirt, which projects laterallyfrom it. This prevents short-circuiting contact between the wire and thebase, or a brace of the bracket structure, as well as short-circuitingcontact with the insulator pin.

The organization of the liner sleeve to include a lateral flange, aswell as a tubular pin-embracing portion, is of particular importancewhen the insulator assembly forms an element of a tensioning andtransposition bracket made in accordance with my prior Patent No.2,356,750, as shown This is because breakage of the frangible body ofone of the insulators makes a short-circuit almost inevitable in theabsence of means effective to prevent short-circuiting. It is, however,highly desirable in insuring against short-circuiting in any tensioningor transposition bracket which in its mounted position is supported bythe line wires inasmuch as it positions the wire with respect to themetal structure of the bracket so that a short-circuit will not be madebetween a line wire and a metal part of the bracket by relative movementbetween the bracket and the wire,'if the frangible body of an insulatorbe broken.

Specifically considered, the material of which the liner is composed isnot critical. Qualitatively the composition of the liner is ofimportance, because it is necessary that the liner should possess theproperty of electrical insulation coupled with substantial toughness,inasmuch as its function is to prevent short-circuiting when thefrangible body of the insulator is broken. A number of suitablematerials are at hand and in common use in the electrical arts. Amaterial I have found ideal for the composition of the liner is the hardred vulcanized fiber which is used in bushings, washers, grommets, andthe like, in electrical equipment. Other suitable tough materials havingthe property of electrical insulation, such as molding materialscomposed of plastics and asbestos fiber and the like compressed andstrong materials possessing good electrical insulating properties, maybe used. These properties are possessed by. the hard vulcanized fiberreferred to above, by Micarta" and by other plastic compositions wellknown in the electrical art.

I do not advance the use of such materials to be new in electricalassemblies, their existence and previous use in such generalassociations being above expressly acknowledged. Primarily my inventionresides in the discovery that in a metal tensioning or transpositionbracket for electrical line wires, a tough electrically non-. conductiveinsulator liner as above disclosed will, upon breakage of the frangibleinsulator body with which it is associated, efiectively preventshort-circuiting; and that it will do so in spite of a tendency for thewire to move into direct contact with the metal structure of the bracketwhen the insulator is broken.

It is to be understood that by the term spoolform, as used herein tovdescribe the bodies of the insulators, I do not mean to define anyspecific shape of insulator, but intend the term to define any of thewell known insulators which are circular in horizontal section, andwhich are provided exteriorly with at least one wire-receiving groove,and which have an interior bore for mounting an insulator body on a pin.Many specific insulator structures commonly in use are comprised withinthe term spool-form as used herein.

I claim as my invention:

1. A wire-contacting insulator assembly consisting essentially of ametallic insulator-mounting pin, a frangible spool-form insulator bodyhaving a circumferential conductor receiving groove and a pin-receivingbore extended therethrough mounted on and surrounding saidinsulator-mounting pin, and a tough electrically insulating liner sleevearranged to contact and detain a wire trained on the insulator when thesaid frangible insulator body is broken comprising a tubularpin-embracing portion surrounding the insulator-mounting pin within thebore of the insulator body and a wire-detaining skirt extended laterallyoutward from the said tubular portion at one end of the bore through thesaid insulator body.

2. A wire-contacting insulator assembly consisting essentially of ametallic insulator-mounting pin, a frangible spool-form insulator body30 6 having a pin-receiving bore extended there-v through mounted on andsurrounding said insulator-mounting pin, said bore being laterallyextended at one end thereof to provide an outwardly open countersunkseat in the said frangible insulator body, and a tough electricallyinsulating liner sleeve arranged to contact and detain a wire trained onthe insulator when the said frangible insulator body is brokencomprising a tubular pin-embracing portion surrounding theinsulator-mounting pin within the bore of the insulator body and awire-detaining skirt extended 1aterally outward from the said tubularportion at one end of the bore through the insulator body and lying inthe said countersunk seat in said body.

ROGERS CASE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 541,332 Patterson June 18, 1895573,092 Locke Dec. 15, 1896 1,000,493 Christensen Aug. 13, 19111,799,580 Burke Apr. 7, 1931 2,356,750 Case Aug. 29, 1944

